The present invention relates to a side airbag apparatus, which deploys and inflates an airbag on one side of an occupant seated in a seat of a vehicle to protect the occupant from an impact applied to the vehicle from the side of the seat.
A side airbag apparatus is known as an apparatus for protecting an occupant from an impact applied to a body-side portion such as a side door of a vehicle in the event of a side collision. The side airbag apparatus includes an inflator, which spews out inflation gas in response to a side collision of a vehicle, and an airbag, which accommodates the inflator in its rear portion and is deployed and inflated with the inflation gas supplied from the inflator. The airbag and the inflator are accommodated in an accommodating portion provided on one side of an occupant seated in a seat, e.g., on a side in a seat back (backrest).
According to the side airbag apparatus having the above-described configuration, when an impact is applied to the body-side portion from the side in the event of side collision, inflation gas is released from the inflator and supplied into the airbag. The air bag is deployed and inflated with the inflation gas to break the seat back and pops out forward. The airbag is deployed and inflated in a narrow space between the occupant seated in the seat and the body-side portion. The airbag thus deployed and inflated has a size and a shape capable of protecting the occupant. An impact transmitted to the occupant from the side through the body-side portion is alleviated by the airbag.
According to the side airbag apparatus, the accommodating portion is located within the seat back. In the accommodating portion with a limited space, the airbag and the inflator are accommodated. Hence, it is required that the airbag be accommodated in a compact form (accommodation state).
For this purpose, according to a side airbag apparatus described in Japanese Laid-Open Patent Publication No. 2008-247212, an airbag, which has been deployed but not inflated, is folded and accommodated. First, in the airbag deployed but not inflated, a front portion thereof located in front of an inflator is folded rearward from front so that the airbag has a transitional state, in which the airbag is thin and long in the up-down direction as shown in FIG. 19A. An upper portion 203 of the airbag 201 in the transitional state, which is located above the inflator 202, is folded downward, and a lower portion 204 of the airbag 201 is folded upward. Thus folding, the airbag 201 is brought into the accommodation state, which is compact in both the front-rear direction and the up-down direction, as shown in FIG. 19B.
When inflation gas is supplied from the inflator 202 to the airbag 201, which has been brought into the accommodation state as described above and accommodated in the accommodation state in the accommodating portion of the seat back, the portions of the airbag 201 are inflated to be unfolded (deployed) through the reversed order of the above-described folding process. This is because the later-folded portion restricts unfolding of the first-folded portion. In such a conventional side airbag apparatus, the upper portion 203 of the airbag 201, which is folded downward into the accommodation state, is rotated forward and upward around an upper folding line to be unfolded (deployed), as shown by alternate long and two short dashed lines in FIG. 19B. At this time, if an obstacle O exists in front of the upper portion 203 in its deploying direction, the upper portion 203 may strongly push the obstacle O forward and upward, i.e., the upper portion 203 may unnecessarily interfere with the obstacle O.
In the airbag 201 in its accommodation state, the lower portion 204 folded upward is rotated forward and downward around a lower folding line to be unfolded (deployed). The upper portion 203 and the lower portion 204 are rotated as described above, and the airbag 201 in its accommodation state is brought into the transitional state, which is thin and long in the up-down direction as shown in FIG. 19A. The folded state of the airbag 201 in its transitional state is unfolded (deployed) forward from behind.